In flotation, a chemical that increases the specific attraction between
collector agents and particle surfaces, or conversely, that increases the
wettability of those surfaces. Pryor, 3
A control adjusting by increments. Strock, 2
The ratio of stress to its corresponding strain under given conditions of
load, for materials that deform elastically, according to Hooke's law. It
is one of the elastic constants. See also:modulus of rigidity;
bulk modulus. Syn:elastic modulus; longitudinal velocity. AGI
The ratio between the pressure in the mass of a soil and the change of
volume caused by such pressure. CF:Poisson's ratio
a. The rate of change of unit shear stress with respect to unit shear
strain, for the condition of pure shear within the proportional limit. For
nonisotropic materials such as wood it is necessary to distinguish between
the moduli of rigidity in different directions. Roark
b. A modulus of elasticity in shear. Symbol: mu or G. Syn:shear modulus;
rigidity modulus; coefficient of rigidity. AGI
a. Nominal stress at fracture in a bend test or a torsion test. In
bending, modulus of rupture is the bending moment at fracture divided by
the section modulus. In torsion, modulus of rupture is the torque at
fracture divided by the polar-section modulus. ASM, 1
b. The load required to break a piece of material, such as a refractory
brick, supported on two spaced and parallel flat bearing edges with the
load applied through a third bearing edge placed midspan and on top of the
piece. ARI
A method of electrolytic refining of silver. Silver plate of 95% to 98%
pure forms the anodes, and thin silver plate forms the cathodes. The
electrolyte consists of a weak, acidulated solution of silver nitrate.
Fay
A diamond-weight calculator which estimates to within a few hundredths the
weights of brilliant-cut diamonds only, by simple measurements of width
and depth of both set or unset diamonds. Hess
The exhalation of carbon dioxide in an area of late-stage volcanic
activity; also, the small opening from which the gas is emitted. Occurs in
Yellowstone National Park. Etymol: French, noxious gas. AGI
Monoclinic silica, SiO2 (silica-G), with quartz in chert from dry
lake beds; also cavity fillings in rhyolitic ignimbrites. Named for Mogan,
Canary Islands.
Titaniferous magnetite with exsolved ulvoespinel. CF:titanomagnetite
A dull white hydrous borate of sodium, Na2 B4 O7 .5H
2 O . Rhombohedral. An alteration film on borax. Locally, octahedral
borax (same as tincalconite). From the Mohave Desert, CA.
See also:octahedral borax
Short name for the Mohorovicic discontinuity separating the Earth's crust
from the mantle. Mather
The never-completed program to drill through the Earth's crust under the
ocean to the Mohorovicic discontinuity in order to provide scientific
knowledge of the Earth's mantle. Hy
The boundary surface or sharp seismic-velocity discontinuity that
separates the Earth's crust from the subjacent mantle. It marks the level
in the Earth at which P-wave velocities change abruptly from 6.7 to 7.2
km/s (in the lower crust) to 7.6 to 8.6 km/s or average 8.1 km/s (at the
top of the upper mantle); its depth ranges from about 5 km beneath the
ocean floor to about 35 km below the continents, although it may reach 60
km or more under some mountain ranges. The discontinuity probably
represents a chemical change from basaltic or simatic materials above to
peridotitic or dunitic materials below, rather than a phase change (basalt
to eclogite); however, the discontinuity should be defined by seismic
velocities alone. It is variously estimated to be between 0.2 and 3 km
thick. It is named in honor of its discoverer, Andrija Mohorovicic
(1857-1936), Croatian seismologist. Abbrev. Moho. Syn:M-discontinuity
AGI
See:Westphal balance
A graphical representation of the stresses acting on the various planes at
a given point. ASCE
The most popular of numerous rock failure criteria. It assumes that there
is a functional relationship between the normal and shear stresses acting
on a potential failure surface. SME, 1
The envelope of a series of Mohr circles representing stress conditions at
failure for a given material. According to Mohr's rupture hypotheses, a
rupture envelope is the locus of points, the coordinates of which
represent the combination of normal and shearing stresses that will cause
a given material to fail. Syn:rupture envelope; rupture line.
ASCE
A ferrous-ammonium sulfate, FeSO4 (NH4 )2 SO4
.6H2 O ; a light green crystalline salt.
Mohr's theory of failure utilizes the well-known stress circle and the
envelope of a family of circles as criteria for failure of materials
subject to biaxial or triaxial stress. Thus Mohr's theory predicts that
failure of materials is due to failure in shear, whereas Griffith's theory
postulates that it is due to failure at crack tips. Lewis